United MileagePlus is re-introducing the ability for members to redeem miles for a United Club membership, starting at 40,000 miles (or $400) for Premier 1K members and moving up in price for lower tier and non-elite members.
Members will also be able to purchase Economy Plus seating for an entire year and pricing and eligibility will vary according to region (domestic 48, North America, intra-Asia, etc.). United is also introducing the option to purchase an annual subscription that will allow members to check one or two bags for an entire year. Pricing has not been announced and will be based on region and number of bags.
Bottom line: Of the new options, only the United Club membership can be purchased with miles. Non-elite members who have to pay for Economy Plus seating and checked bags may be willing to pay a higher fee upfront to receive benefits on all flights for an entire year. Keep in mind that United MileagePlus Explorer cardholders ($95 annual fee, waived the first year) receive one free checked bag and elite members receive complimentary Economy Plus seating and free checked bags.